Japan Nuclear Crisis: Workers Fail to Stabilize Plant; U.S. Water Pumps Might Be the Answer

"It's like a squirt gun, using a squirt gun against a raging forest fire. They're overwhelmed, they're floundering, they don't know what to do," said Dr. Michio Kaku, a theoretical physicist who has been consulting for ABC News.

Next, Japan's Self Defense Forces poured 30 tons of water from special pumper trucks. Workers were able to pump the water without leaving the trucks. Officials are still determining how effective the water was in cooling the fuel pond.

The water trucks and helicopters were used, in part, because radiation levels are too high for workers to be directly in the plant for extended periods.

"At a certain point, they're going to have to abandon ship, they're committing a suicide mission to go in there. The radiation levels are near lethal right now…you're committing suicide to spend large amount of time there," Kaku said.

The International Atomic Energy Agency said at a press conference today that the situation at the plant remains "serious" but has not worsened since yesterday.

Radiation levels have soared in some places around the plant in the last 24 hours. The highest readings outside the area have come 30 kilometers northwest of the plant, where levels of 170 millisieverts were measured.

The level of radiation in Tokyo remains low, officials said, and is not a danger to humans.

The IAEA said it was concerned about unit 4's fuel pond. Officials said that they have received no new information on how much water remains in the pond. The last time they received a temperature reading was three days ago.

Experts say that the spent fuel ponds might be more dangerous than the core reactors. Fuel ponds hold old fuel rods that must be kept in water at all times. Of particular concern are the fuel ponds for units 3 and 4.

"Hollywood likes to focus in on the meltdown, the melted core exposed uranium. But old fuel is actually more dangerous than the meltdown because there's more radiation in an unguarded spent fuel pond than the reactors," Kaku said. "You could have a fire. It would go up like fireworks, like Roman candles."

The spent fuel rods are kept in pools of water to prevent them from overheating and ultimately melting down. The outer shell of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area. Along with the escalating temperatures in unit 3 and 4, unit 5 and 6 are also experiencing rising temperatures in their fuel ponds.

Japan's nuclear safety agency and Tokyo Electric Power Co., which operates the complex, denies water is gone from the pool. Utility spokesman Hajime Motojuku told the Associated Press the "condition is stable" at unit 4.

"I want to be very clear," said Obama. "We do not expect harmful levels of radiation to reach the West Coast, Hawaii, Alaska or U.S. territories in the Pacific."

Overnight, Obama spoke with the Japanese Prime Minister Naoto Kan to express his sympathy and offer assistance.

"The president expressed his extraordinary admiration for the character and resolve of the Japanese people, and his confidence that Japan will make a full recovery from this disaster," said the White House in a statement.